Maybe I'm an idiot and this is elementary to everyone but me.  Maybe 
it's not a function of asterisk.  It's driving me nuts.
When I'm on a call and another one comes in for me, in general I *don't*
want to put the current call on hold and pick up; I almost always want 
to drop the current call ("Talk to you later.  I've got another
call.")
and pick up the other one.
But if I flash, asterisk puts the call on hold.  If I hang up and let it 
ring, oftentimes by the time a ring or two has gone by the second caller 
has been sent to voicemail, and I don't think I can barge on voicemail. 
  One ring doesn't appear to behave any differently than a flash.
What is the way to do this?  Is it an RTFM that I have missed?
Thanks.
B.